With brother Charles, transformed family refining business into America's largest private company. Father, Fred C. Koch (d. 1967), invented method of turning heavy oil into gasoline. Sons Charles, David, Frederick and William inherited Koch Industries after father's death. Charles and David bought out William and Frederick for $1.1 billion in 1983; fraternal fight over deal settled in 2001.

Employs 80,000 workers in 60 countries. Purchased Invista, maker of Lycra and Coolmax fabric, in 2004 for $4.2 billion. Dropped $21 billion on paper and building-supply vendor Georgia-Pacific the following year. Holds chemical engineering degrees from MIT; pledged $100 million to alma mater for cancer research last year. Pledged another $100 million to New York's Lincoln Center this July.

David Koch, who now lives in New York, was raised in Wichita He earned two degrees in chemical engineering from the Massachusetts Institute of Technology in the early 1960s. He and his wife, Julia Flesher Koch, have been married more than 20 years and have three children.

He was diagnosed with prostate cancer 25 years ago, and he has given vast sums toward cancer research in the quarter century since then. David Koch has pledged or contributed a total of more than $1.3 billion to assist causes from cancer research to medical centers, educational institutions, arts and cultural institutions and public policy organizations. The money has come through personal gifts and the David H. Koch Foundation.

In 1980, he was the Libertarian Party’s nominee for vice president. His ticket, with Ed Crane, received just 1 percent of the popular vote. Ronald Reagan won.